Immunogenicity of carcinogen-induced tumors in inbred rats will be accentuated by mechanical dissociation of tumor specimens and treatment of cells with the enzyme, neuraminidase, of V. cholerae origin. Host immune response will be quantitated by in vitro testing of lymphoblastic transformation of host peripheral blood lymphocytes and definition of cytotoxic action of lymphocytes so sensitized. Role of host serum blocking factors in these reactions will be studied.